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  #16 (permalink)  
Old 01-22-2011, 03:31 PM
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Quote:
Originally Posted by WDCreech
Since this is a street engine, and your looking for milage, go with the 7J2 heads. The smaller valves won't make any difference on the street and you wouldn't have to mill them much to get your compression where it should be. I would have screw in rocker studs installed in them, but for a 350, I think they would be the better head.
X 2 I agree

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Old 01-22-2011, 03:41 PM
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Quote:
Originally Posted by recnepswilliams
how much would i need to mill the 7j2 heads if i choose them (and how can i fix that pesky missing exhaust bolt problem?)

what kind of mileage could i expect? i have a 1980 el camino with a chevy 350 and when i had the quadrajet on it i got 22 mpg, it has the same gears, but i read that the longer stroke pontiac motor should be more fuel efficient.
Get beret and an old CD and CC them to know for sure. The charts I have seen are vague at best. Like cobalt said in the past after years of use and who knows if the heads you have , were milled allready, the only way to know for sure is to CC them.
I found a set of 7H1 heads I am using on my street 389/400 and the chart said they were 7.6 to 1 compression. nothing said about chamber size. One other site said they were 80 CC s . They were actually 91 CCs.
Wallace was right about the compression ratio, i figured out after aI reverse calculated compression ratio to get chamber size.
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Old 01-22-2011, 03:43 PM
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small valve heads work better for a street 350 as there tends to be less valve shrouding which is an issue from what I have been able to gather from my research.
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Old 01-23-2011, 05:03 PM
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if you have ever installed a pontiac intake you know that you have to put all the bolts in get them snug and then first tighten the bolt from the timingchain cover to the intake to seal the gromet.

doing this changes the location of the runners.
so when you port match the intake, you must cut the waterneck off. its pretty easy to do, just make sure you ct right behind the front bolt so that the rest of the intake will seal the oil holes.
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Old 01-23-2011, 06:23 PM
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The 7j2 heads i have were recently rebuilt from what i was told (the seemed to seal fine)

so i'll be better off to have the 7j2 heads milled about .050, screw in rocker studs, and port match the intake to the heads?

and that does make sense about cutting the water passage off, i didn't look at it that way, the timing cover can't really slide back towards the manifold.

would there be any other option besides cutting the front off of the intake? another way to keep it all lined up maybe?

and the 275DEH was a dual patter cam, and i have flowtech headers, and i plan to use them since they fit in the car perfect before without any bending, and they have 4 tubes per header.

i'm also kind of stuck on the price difference between a 700r4 and a th350, my th350 already ran and didn't slip, so i figured if i take it apart and check clearances and everything i could reuse it with a new torque converter. but i remembered something else, i have a muncie 4-speed with the clutch/brake assembly all i would need is the clutch linkage, and i hear that rebuilding a 4 speed is easier, but would i save money doing that? or would the 700r4 be the best bet overall?
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  #21 (permalink)  
Old 01-23-2011, 06:35 PM
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Quote:
Originally Posted by recnepswilliams
The 7j2 heads i have were recently rebuilt from what i was told (the seemed to seal fine)

so i'll be better off to have the 7j2 heads milled about .050, screw in rocker studs, and port match the intake to the heads?

and that does make sense about cutting the water passage off, i didn't look at it that way, the timing cover can't really slide back towards the manifold.

would there be any other option besides cutting the front off of the intake? another way to keep it all lined up maybe?

and the 275DEH was a dual patter cam, and i have flowtech headers, and i plan to use them since they fit in the car perfect before without any bending, and they have 4 tubes per header.

i'm also kind of stuck on the price difference between a 700r4 and a th350, my th350 already ran and didn't slip, so i figured if i take it apart and check clearances and everything i could reuse it with a new torque converter. but i remembered something else, i have a muncie 4-speed with the clutch/brake assembly all i would need is the clutch linkage, and i hear that rebuilding a 4 speed is easier, but would i save money doing that? or would the 700r4 be the best bet overall?
So did you CC the heads?
I wouldnt worry about hackin an intake.
Run a comp cams XE 262 ( part # 51-222-4)
mill the heads down to 70 CC chambers, youll end up at 9.49 - 1 static and with the cam you have you will have 7.99 - 1 dynamic. should be perfect for the combo you want on pump gas. Its the same combo I am putting together after much research and asking questions and math also.
Oh I almost forgot, line bore your block, then deck it to .006 above the piston tops.make sure you have pistons with a stock or above stock compression height. 1.717 is stock. some of the speed pro s are 1.72 which is good. You want to run a .039 or a .042 head gasket to get a good quech, which is also the reason you want to deck the block.
Use flat tops w 6 cc reliefs.
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Old 01-24-2011, 03:29 PM
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I'm limited to using the compcams 275DEH camshaft, since it's the one i already bought, i don't have a ton of money to spend.

I don't remember which pistons i have, but our local machine shop ordered them, so they should be the right height.

I have another question, if i go with the muncie 4 speed i have what all do i need besides the clutch to make it all work?

I have the pedal assembly, but what about linkage between the clutch and pedal assembly? what else might i need?
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Old 01-24-2011, 06:44 PM
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Quote:
Originally Posted by recnepswilliams
I'm limited to using the compcams 275DEH camshaft, since it's the one i already bought, i don't have a ton of money to spend.

I don't remember which pistons i have, but our local machine shop ordered them, so they should be the right height.

I have another question, if i go with the muncie 4 speed i have what all do i need besides the clutch to make it all work?

I have the pedal assembly, but what about linkage between the clutch and pedal assembly? what else might i need?
That cam should actually work quite well.
You need to know the deck clearance for the piston(deck height) or you will be forced to keep the compression a little lower than would be optimum.
You need to keep a good quench factor involved here so you can keep the compression up so as to run pump gas and get performance without detonation.
It isnt hard to CC a chamber, it isa MUST. You cant guess at chamber sizes and have the whole thing work out right.
Go to E Bay and enter Beret in the search box. I bought a plastic ( acrylic) one for obvious reasons.You need one to CC the heads or pay the machine shop to check them and mill them accordingly.
As far as the 4 speed, you need the through rod for the pedal through the firewall, a z bar (bellcrank) , bell housing, clutch fork, pivot ball and bracket, for the frame to support the one end of the Z bar and the ball stud for the other end of the z bar.
Do some research on Quench and quench pads in an internal combustion engine. It will shed some very USEFULL and valuable info you NEED to KNOW for your build if you want it to turn out right.
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Old 01-24-2011, 06:49 PM
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With the cam and heads you are proposing you will have to mill the heads to 68 CCs to get the static compression up to 9.69 and the dynamic up to 7.82
That is assuming you get the block decked to .006 in. and run a .039 head gasket. Giving you a very comfortable .045 quench.
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Old 01-25-2011, 01:27 PM
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I'll read through Jim Hand's book a little more and see if there was anything in there on quench.

what would the cost of milling the heads typically be?
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Old 01-25-2011, 05:07 PM
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Quench is the area of the cylinder head that is flat and would to do hit the piston if it were to come up high enough in the cylinder. You dont want that naturally, but you want it to be a close non collision,.what it does is force the combustible mix into the part of the chamber/cylinder where the valves are. It creates swirl and helps cool the mix ,therefore helping to keep detonation down , so you can run a little higher compression. Some guys call it artificial octane. Try google it. My dinners ready or I would elaborate more.
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